Data transmission methods for use in data communications between the main unit of an image processing device and peripheral devices related thereto include the following.
Philips, I.sup.2 C bus system PA1 SGS--Thomson DS link system
In this system, serial data and a serial clock are transmitted by two wires. The data and clock are physically separated, and data transmission/reception and reproduction are possible by the simplest method. The I.sup.2 C bus is described, for example, in Philips' I.sup.2 C bus instruction manual (January 1992).
In this system, a data signal and strobe signals are transmitted by two wires. A clock signal is reproduced by means of the data signal and strobe signal. When the transmitted data changes to a different value, only the data signal changes. When the transmitted data is the same value, only the strobe signal changes. For example, if the transmitted data in the data signal changes from "0".fwdarw."1", or "1".fwdarw."0", then the strobe signal does not change. If the transmitted data in the data signal does not change, e.g., "0".fwdarw."0", or "1".fwdarw."1", then the strobe signal only changes. Therefore, by adopting an exclusive-OR operation for the data signal and strobe signal, it is possible to reproduce a clock signal. The DS link system is introduced in Nikkei Electronics, Vol. 675, (4.sup.th November 1996, pp. 167-171). In consumer-oriented devices, such as game devices, it is necessary to use a data transmission system and interface connection standard which can be implemented at low cost. However, in the aforementioned I.sup.2 BUS system, since the transition edge of the data signal has the same timing as the transition edge of the clock, it is not possible to use the clock signal directly on the data reproducing (demodulating) side. Furthermore, in the latter DS link system, exclusive-OR logic is applied to the data signal and strobe signal, to reproduce a synchronizing clock. The data signal must be sampled using this clock. Therefore, the level of simplicity of the interface circuit structure does not adequately satisfy the conditions for domestic game devices, where low cost is a very important requirement.
Consequently, it is an object of the present invention to provide a data transmission system for an interface having an inexpensive circuit composition, which can be applied to an image processing device, such as a domestic game system. It is a further object of the present invention to provide a data transmission system for an interface, whereby data can be separated from a signal carrying data by means of a simple circuit composition.
It is a further object of the present invention to provide a game device and a related peripheral device comprising interfaces, whereby data can be separated from a signal carrying data by means of a simple circuit composition.
It is a further object of the present invention to provide basic technology for developing various types of peripheral devices, by proposing novel interface technology between a game device and peripheral device.